Motor and drive control system thereof

ABSTRACT

Provided is a motor having a magnetic polar unit in which a permanent magnetic polar array having arranged therein alternately a plurality of permanent magnetic polar elements in alternate opposite poles is made to face a plurality of electromagnetic coil arrays alternately excited at opposite poles, and the permanent magnetic polar array is made to move thereby; wherein the motor further comprises a sensor for detecting the periodical magnetic change accompanying the movement of the permanent magnetic polar array, the output of the sensor is directly returned as a direct drive waveform to the electromagnetic coils, and this drive circuit forms the excitation signal based on the return signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. Ser. No.12/497,300 filed Jul. 2, 2009, which is a continuation of U.S. Ser. No.11/725,522, filed Mar. 19, 2007, which is a divisional patentapplication of U.S. Ser. No. 11/445,396 filed Jun. 1, 2006, now U.S.Pat. No. 7,211,974 issued May 1, 2007 which is a divisional of U.S. Ser.No. 11/078,960 filed Mar. 11, 2005, now U.S. Pat. No. 7,095,155 issuedAug. 22, 2006, claiming priority to Japanese Patent Application No.2004-071417 filed Mar. 12, 2004, all of which are hereby expresslyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to various motors constituted to rotate arotor or move a slider formed from a permanent magnet or ferromagneticmaterial by linearly arranging coils that generate magnetic poles andsequentially switching the current to be applied to the coil, a magneticstructure to be employed in such a motor, and a power driver employingthis motor as its drive source. The present invention may be employed inthe likes of an electric vehicle, electric cart and electric wheelchair,as well as an electric toy, electric airplane, small electronicappliances and MEMS as the foregoing power driver.

DESCRIPTION OF THE RELATED ART

An AC motor driven with a frequency signal such as an alternatingcurrent can be broadly classified into two types; namely, a synchronousmotor and an induction motor. A synchronous motor is a motor that uses alayered core of a permanent magnet or a ferromagnetic material such asiron in the rotor, and rotates at a rotation speed that is the same asthe speed of the rotating magnetic field determined based on the powersupply frequency.

Depending on the type of rotor, there are various types of motors suchas a magnetic type which uses a permanent magnet, a coil type with acoil wound thereto, and a reactance type which uses a ferromagneticmaterial such as iron. Among the above, with the magnetic type motorrotates by the permanent magnet of the rotor being pulled with therotating magnetic field of the stator. Meanwhile, the induction motor isa motor that rotates by generating a separate magnetic field with theelectromagnetic induction effect to a rotor having a box-shapedconduction wire.

Among the foregoing motors, there is a motor that does not rotate, butrather moves linearly or moves freely on a flat surface. This kind ofmotor is generally referred to as a linear motor, and moves thepermanent magnet or ferromagnetic material mounted thereon by linearlyarranging coils that generate magnetic poles and sequentially switchingthe current to be applied to the coil. The linearly disposed coil arrayis the stator, and the rotor corresponds to a flat slider that slidesthereabove.

As a magnetic synchronous motor, for instance, there is a smallsynchronous motor described in the gazette of Japanese Patent Laid-OpenPublication No. H8-51745 (Patent Document 1). This small synchronousmotor, as shown in FIG. 1 of Patent Document 1, is constituted bycomprising a stator core 6 wound with an excitation coil 7, and a rotor3 having a rotor core 2 having a magnet 1 build therein and in which theNS poles are aligned in even intervals around the peripheral facethereof.

SUMMARY OF THE INVENTION

Nevertheless, with the motor explained in the description of the relatedart, the weight became massive in comparison to the generated torque,and there is a problem in that the motor would become enlarged whenattempting to increase the generated torque. Thus, an object of thepresent invention is to provide a motor suitable for miniaturization andsuperior in torque and weight balance.

In order to achieve the foregoing object, the present invention providesa motor drive system comprising a movable body and a plurality ofelectromagnetic coils in which the plurality of electromagnetic coils isdisposed as a stator in a non-contact manner on the movable body towhich a plurality of permanent magnets alternately magnetized atopposite poles is continuously disposed thereon, and the movable body iscapable of moving based on the attraction—repulsion between the movablebody and electromagnetic coils generated by supplying an excitationcurrent as a direct drive waveform to the electromagnetic coils; whereina sensor for detecting the periodical magnetic field change caused bythe movement of the permanent magnet is provided, and the output of thesensor is directly supplied as the excitation current to theelectromagnetic coils.

In a preferred embodiment of the present invention, the movable body isconstituted to have a plurality of constitutions in which the hetropolararrangement of two different permanent magnets constitutes a pair, and,when the position between the hetropolar arrangement constituting a pairis 2π, the sensor is able to linearly detect the arbitrary positionbetween the 2π, and the sensor is provided to the electromagnetic coilphase.

Also provided is a motor drive system provided with a movable bodyconstituted to have a plurality of constitutions in which the hetropolararrangement of permanent magnets constitutes a pair, in which theposition between the hetropolar arrangement constituting a pair is setto 2π, and the movable body is moved based on the attraction—repulsionwith non-contact electromagnetic coils; wherein the sensor is able tolinearly detect the arbitrary position between the 2π, and the sensor isprovided to the electromagnetic coil phase. The arbitrary positionsignal level obtained from the sensor corresponding to theelectromagnetic coil phase is returned to the electromagnetic coils.

The present invention also provides a motor comprising magnetic polarmeans in which a permanent magnetic polar array having arranged thereinalternately a plurality of permanent magnetic polar elements inalternate opposite poles is made to face a plurality of electromagneticcoil arrays alternately excited at opposite poles, and the permanentmagnetic polar array is made to move thereby; wherein the motor furthercomprises a sensor for detecting the periodical magnetic changeaccompanying the movement of the permanent magnetic polar array, and theoutput of the sensor is directly returned to the electromagnetic coils.In a more detailed embodiment of the present invention, the coil arrayis formed from a two-phase pair of A and B phases, the permanentmagnetic polar array is interposed between the A and B phases, A and Bphases shift the phase for establishing the coil, a sensor for the Aphase coil and a sensor for the B phase coil are provided, and the phasefor establishing the A phase coil sensor and the B phase coil sensor isshifted. A plurality of patterns of excitation signals is suppliedrespectively to the A phase coil and the B phase coil. Regardless of atwhich position the permanent magnetic polar array is stopped, at leastone signal among the plurality of patterns of excitation signals is setto be the excitation state based on the output from the A phase sensorand the B phase sensor. The sensor is a hall element sensor foroutputting an analog detection value. PWM control is added to the sensoroutput value based on the drive request torque of the motor, and thecontrol signal is supplied to the excitation coils.

The present invention further provides a motor regenerative drive systemto be used in the regeneration of the motor, wherein provided isregeneration control means for controlling the regeneration based on thesensor signal, and the control means has means for forming aregenerative enabling signal from the sensor signal, means forcontrolling the duty of the regenerative enabling signal based on theload status, and means for arbitrarily controlling the regeneration ofthe motor based on the duty.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the frame format and principle of operationof the magnetic structure pertaining to the present invention;

FIG. 2 is a diagram showing the principal of operation subsequent toFIG. 1;

FIG. 3 is an equivalent circuit diagram showing the connection state ofthe electromagnetic coils;

FIG. 4 is a perspective view of the motor;

FIG. 5 is a block diagram of the drive circuit for supplying anexcitation signal to a coil array;

FIG. 6 is a control circuit block diagram for returning the digitaloutput of the sensor directly to the coil drive circuit;

FIG. 7 is the control waveform diagram thereof;

FIG. 8 is a waveform diagram showing the PWM control processingoperation from the digital output of the sensor;

FIG. 9 is a control circuit block diagram for returning the analogoutput of the sensor directly to the coil drive circuit;

FIG. 10 is the control waveform diagram thereof;

FIG. 11 is a control circuit block diagram for achieving the control ofthe hysteresis level in relation to the analog output value of thesensor;

FIG. 12 is a control waveform diagram in the case when the hysteresislevel is small;

FIG. 13 is a control waveform diagram in the case when the hysteresislevel is large;

FIG. 14 is a block diagram of the PWM control circuit based on theanalog output sensor;

FIG. 15 is a waveform diagram showing the PWM control operation thereof;

FIG. 16 is a block diagram showing another example of the coil drivecircuit;

FIG. 17 is the drive waveform diagram thereof;

FIG. 18 is a block diagram in the case of employing the presentinvention in a stepping motor;

FIG. 19 is a waveform diagram of sensor direct drive system in astepping motor;

FIG. 20 is a block diagram of the digital regeneration/power generationcontrol based on an analog sensor comprising a window comparator havinga hysteresis adjustment electronic VR;

FIG. 21 is a waveform diagram showing a case where the hysteresisadjustment electronic VR is small and the regenerative energy ismaximum;

FIG. 22 is a waveform diagram showing a case where the hysteresisadjustment electronic VR is maximum and the regenerative energy isminimum;

FIG. 23 is a functional block diagram of the incoming control from therespective phase coils;

FIG. 24 is a block diagram showing the energy converter of theregenerative current; and

FIG. 25 is a diagram showing the structure where the respective phasecoils and the rotor, which is formed from a permanent magnet, are facingeach other in the radial direction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 and FIG. 2 are diagrams showing the principal of operation of themotor pertaining to the present invention. This motor has a constitutionwhere a third permanent magnet 14 is interposed between a first coilpair (A phase coil) 10 and a second coil pair (B phase coil) 12. Thecoils and permanent magnet may be constituted circularly (arc, circle)or linearly. When formed circularly, either the permanent magnet or thecoil phase functions as the rotor, and, when formed linearly, one of theabove becomes a slider.

A first coil pair 10 comprises a constitution in which the coils 16alternately excitable to the opposite poles are sequentially aligned ina prescribed spacing, preferably an even spacing. FIG. 5 is anequivalent circuit diagram of this first coil pair. According to FIG. 1and FIG. 2, as described later, with a two-phase excitation coil, allcoils are excited to be constantly driven against the two-phase excitingcoil during the start-up rotation (2π) with the foregoing polarity.Therefore, a drivee means such as a rotor or slider can be rotated anddriven at high torque.

As shown in FIG. 3(1), a plurality of electromagnetic coils 16 (magneticunit) to be alternately excited at opposite poles is connected seriallyin even spacing. Reference numeral 18A is a block showing the drivecircuit for applying a frequency pulse signal to these magnetic coils.When an excitation signal for exciting the coils is sent from theexcitation circuit to the electromagnetic coils 16, the respective coilsare pre-set to be excited such that the direction of the magnetic poleswill alternate between the adjacent coils. As shown in FIG. 3(2), theelectromagnetic coils 16 may also be connected in parallel. Thestructure of these coils are the same for both A and B phase coils.

When a signal having a frequency for alternately switching, inprescribed cycles, the direction of the polarity of the suppliedexcitation current is applied from the excitation circuit 18A to theelectromagnetic coils 16, as shown in FIG. 1 and FIG. 2, a magneticpattern which alternately changes the polarity on the side facing therotor 14 from N pole→S pole→N pole is formed in the A phase coil pair10. When the frequency signal becomes a reverse polarity, a magneticpattern is generated for alternately changing the polarity, which is onthe third magnetic body side, of the first magnetic body from S pole→Npole→S pole. As a result, the excitation pattern appearing in the Aphase coil pair 10 will periodically change.

Although the structure of the B phase coil pair is the same as the Aphase coil pair, the electromagnetic coils 18 of the B phase coil pairdiffers with respect to the point that it is aligned by beingpositionally shifted in relation to the [electromagnetic coils] 16 ofthe A phase coil pair. In other words, the array pitch of the coil inthe A phase coil pair and the array pitch of the B phase coil pair aredisposed in an offset so as to have a prescribed pitch difference(angular difference). This pitch difference is preferably the (singlerotation) of the angle in which the permanent magnet 14 movescorresponding to 1 cycle (2π) of the excitation current frequency inrelation to the coils 16, 18; for instance π/6 (π/(2/M): M is the numberof sets of permanent magnet (N+S) where M=3).

The permanent magnet is now explained. As depicted in FIG. 1 and FIG. 2,the rotor 14 formed from a permanent magnet is disposed between atwo-phase coil pair, and a plurality of permanent magnets 20 (marked outin black) having alternately reverse polarities is aligned in a line(linearly or in an arc) in prescribed spacing, preferably in evenspacing. An arc shape includes loops such as a perfect circle or an ovalshape, as well as indefinite circular structures, half circles, fanshapes, and so on.

The A phase coil pair 10 and B phase coil pair 12 are disposed via equalspacing, and a third magnetic body 14 is disposed between the A phasecoil pair and B phase coil pair. The array pitch of the permanent magnet20 is roughly the same as the array pitch of the magnetic coil in the Aphase coil 10 and B phase coil 12.

Next, the operation of the magnetic structure in which the foregoingthird magnetic body is disposed between the first magnetic body 10 andsecond magnetic body 12 is explained with reference to FIG. 1 and FIG.2. Let it be assumed that, based on the foregoing excitation circuit(reference numeral 18 illustrated in FIG. 3; to be described in detaillater), the excitation pattern shown in FIG. 1(1) is being generated ata certain moment in the electromagnetic coils 16, 18 of the A phase coiland B phase coil.

Here, a magnetic pole in the pattern of →S→N→S→N→S→ is generated in therespective coils 16 on the surface facing the side of the permanentmagnet 14 of the A phase coil 10, and a magnetic pole in the pattern of→N→S→N→S→N→ is generated in the coil 18 on the surface facing the sideof the permanent magnet 14 of the B phase coil 12. In the diagrams, themagnetic relation between the permanent magnet and the respective phasecoils is illustrated, and a repulsive force will arise between the samepoles and an attractive force will arise between opposite poles.

The next instant, as shown in FIG. 1(2), when the polarity of the pulsewave applied to the A phase coil via the drive circuit 18 is reversed, arepulsive force will arise between the magnetic pole generated to thecoils 16 of the A phase coil 10 and the magnetic pole of the permanentmagnet 20. Meanwhile, since an attracting force is generated between themagnetic pole generated to the coils 18 of the B phase coil 12 and themagnetic pole on the surface of the permanent magnet, as shown in FIG.1(1) to FIG. 2(5), the permanent magnet 14 will sequentially moverightward in the diagram.

A pulse wave having a phase lag in comparison to the exciting current ofthe A phase coil applied to the coils 18 of the B phase coil 12, and, asshown in FIGS. 2(6) to (8), the magnetic pole of the coils 18 of the Bphase coil 12 and the magnetic pole on the surface of the permanentmagnets 20 repel against each other, and move the permanent magnet 14further rightward. FIG. 1(1) to FIG. 2(8) illustrate a case where therotor 14 engages in a rotation corresponding to π, and FIG. 3(9) onwardillustrate a case where such rotor 14 engages in a rotationcorresponding to π→2π. As described above, the rotor will rotate bysupplying a drive current (voltage) signal of a prescribed frequencywith a shifted phase to the A phase coil array and B phase coil array.

When the A phase coil array, B phase coil array and the permanent magnetare formed in an arc, the magnetic structure depicted in FIG. 1 willbecome a structure of a rotating motor, and, when these are formedlinearly, the magnetic structure thereof will become a linear motor.Excluding the portions of the permanent magnet such as a case or rotorand the electromagnetic coil can be reduced in weight by employing anon-magnetic body such as resin (including carbon) or ceramics, and arotating power drive superior in a power-weight ratio can be realizedwithout generating iron loss as a result of opening the magnetic circuitwithout using a yoke.

According to this magnetic structure, since the permanent magnet is ableto move upon being subject to the magnetic force from the A phase coiland the B phase coil, the torque upon moving the permanent magnet willincrease, and, since the torque/weight balance will become superior, asmall motor capable of driving at a high torque can be provided thereby.

FIG. 3(1) shows the respective circuits of the A phase coil and B phasecoil in a case where the plurality of coil arrays is formed serially,and FIG. 3(2) shows the respective circuits of the A phase coil and Bphase coil in a case where the plurality of coil arrays is formed inparallel.

FIG. 4 is a perspective view of the motor, wherein FIG. 4(1) is aperspective view of the motor; FIG. 4(2) is a schematic plan view of therotor (third magnetic body); FIG. 4(3) is a side view thereof; FIG. 4(4)is a diagram showing an A phase electromagnetic coil (first magneticbody); and FIG. 4(5) is a diagram showing a B phase electromagnetic coil(second magnetic body). The reference numerals used in FIG. 4 are thesame as the structural components corresponding to the foregoingdiagrams.

The motor comprises a pair of A-phase magnetic body 10 and B-phasemagnetic body 12 corresponding to a stator, as well as the thirdmagnetic body 14 constituting the rotor, and a rotor 14 is rotatablydisposed around the axis 37 and between the A-phase magnetic body andB-phase magnetic body. The rotating axis 37 is fitted into an opening inthe center of the rotor such that the rotor and rotating axis can rotateintegrally. As shown in FIGS. 4(2), (4) and (5), six permanent magnetsare provided to the rotor in even spacing around the circumferentialdirection thereof, polarities of the permanent magnets are made to bemutually opposite, and six electromagnetic coils are provided to thestator in even spacing around the circumferential direction thereof.

The A phase sensor 34A and B phase sensor 34B are provided to the innerside wall of the case of the A phase magnetic body (first magnetic body)via a phase shift (distance corresponding to π/6). The A phase sensor34A and B phase sensor 34B are subject to mutual phase shifts forproviding a prescribed phase different to the frequency signal to besupplied to the A phase coil 16 and the frequency signal to be suppliedto the B phase coil 18.

As the sensor, it is preferable to use a hall element employing the halleffect and which is capable of detecting the position of the permanentmagnet from the change in the magnetic pole pursuant to the movement ofthe permanent magnet. As a result of employing this sensor, when the Spole of the permanent magnet to the subsequent S pole is set to 2π, thehall element will be able to detect the position of the permanent magnetregardless of where the permanent magnet is located. As the hallelement, a method of generating a pulse may be employed, or a method ofoutputting an analog value according to the magnetic pole intensity mayalso be employed.

FIG. 5(1) and FIG. 5(2) respectively show the drive circuits of the Aphase magnetic body formed from an A phase coil array and the B phasemagnetic body formed from a B phase coil array.

This circuit includes switching transistors TR1 to TR4 for applying theoutput waveform of the sensor as an excitation current to the A phaseelectromagnetic coil or B phase electromagnetic coil. Here, when the Aphase sensor output as the signal is “H”, “L” is applied to the TR1gate, “L” is applied to the TR2 gate, “H” is applied to the TR3 gate,and “H” is applied to the TR4 gate. Then, TR1 and TR4 will be turned on,and the excitation current as the output from the sensor having an IA1is applied to the A phase coil. Meanwhile, when then A phase sensoroutput as the signal is “L”, “H” is applied to the TR1 gate, “H” isapplied to the TR2 gate, “L” is applied to the TR3 gate, and “L” isapplied to the TR4 gate. Then, TR2 and TR3 will be turned on, and theexcitation current having an IA2 orientation will be applied to the Aphase coil. Further, when “H” is applied to TR1 and TR3 and “L” isapplied to TR2 and TR4, this will enter an HiZ state, and current willnot be supplied to the electromagnetic coil. The same applies regardingthe excitation to the B phase coil illustrated in FIG. 5(2).

FIG. 6 is a processing circuit of the control signal supplied to the Aphase drive circuit and B phase drive circuit. The digital output fromthe A phase sensor 35A is supplied to the EX-NOR gate 80, and thedigital output from the B phase sensor 35B is supplied to the EX-NORcircuit 82. Reference numeral 92 is a formation means of the controlsignal for selecting whether to supply the output from the sensor to theforegoing drive circuit as is, or to change (PWM) the duty of the sensoroutput value, and reference numeral 93 is a formation of the controlsignal for determining whether to make the direction of rotation of therotor formed from a permanent magnet a normal rotation or a reverserotation. Either pattern (polarity) of the A phase coil and B phase coilmay be reversed for normal rotation and reverse rotation. Each of thesemeans is realized with a microcomputer. Reference numeral 88 is the PWMconverter, and is capable of controlling the motor torque by convertingand controlling the analog quantity from the sensor output into a logicquantity via PWM control (current control). Reference numeral 90 is aswitching circuit unit for switching the selection of the signal formedwith the PWM converter 88 or the signal directly obtained from thesensor, and supply thereof to the A phase drive 84 or B phase drive 86.

FIG. 7 is a diagram showing the output waveforms of the respective phasesensors and the excitation signal pattern to be supplied to the drivecircuits of the respective phase coils. As a result of the establishedposition phase of the A phase sensor and B phase sensor being mutuallyshifted, a phase difference in the output value thereof will also becomeapparent. The control circuit of 8 described above directly supplies theoutput (1) of the A phase sensor as a direct drive waveform to thedriver 84 of the A phase coil. The A1 phase drive waveform (3) is thecontrol signal having the current orientation of terminal A1→terminal A2of the A phase coil array depicted in FIG. 5, and A2 phase drivewaveform (4) is the control signal having the current orientation of A2terminal→A1 terminal. As shown in FIG. 5, a plurality of coil excitationpatterns of the A1 phase waveform and A2 phase waveform is formed fromthe A phase sensor output, and this is output to the excitation circuit(coil drive circuit). The same applies for the B phase coil. FIG. 7illustrates a case of directly supplying the sensor output to the drivecircuit.

Regardless of the position of the permanent magnet of the rotor, evenassuming that the A phase sensor output and B phase sensor output areboth “L”, since the respective levels of the A2 phase drive waveform andB2 phase waveform are “H”, as a result of this being supplied to thedrive circuit, the A phase coil array and B phase coil will both beexcited, and try to rotate the rotor comprising the permanent magnet. Inother words, regardless of at which position the permanent magnet isstopped, the rotation of the rotor can be started by directly returningthe sensor output to the driver. As described above, since the sensoroutput can be directly returned to the drive circuit, it is possible tosimplify the constitution of the control circuit.

FIG. 8 is a control waveform diagram showing the coil array beingsubject to PWM drive. FIG. 8(1) to (6) are the same as FIG. 7. FIG. 8(7)shows the sinusoidal wave output to be applied to both ends of thepotential of the A phase coil array, and the frequency of thissinusoidal wave will change pursuant to the duty command value. As aresult of acquiring this sinusoidal wave output and the AND of thedigital output value (synthesis of (1) and (3)) of both ends of the Aphase coil, the output value of the A phase coil can be subject to dutyconversion. The same applied to the B phase coil array.

FIG. 9 is a control circuit for directly driving the driver with ananalog sensor; that is, a block diagram showing the analog output valueof the sensor being directly supplied to the excitation coil. Referencenumeral 100 is an amplifier of the sensor output. The polarity of thesensor output is controlled based on the normal rotation/reverserotation circuit 101 of the rotor. Reference numerals 102 and 104 areauto gain controls. FIG. 10 is a diagram showing the analog output valueof the respective phase sensors, and the drive voltage waveform of therespective phase coil arrays to which this analog output value has beensupplied.

FIG. 11 is a diagram showing the digital drive circuit based on ananalog sensor, and reference numeral 130 is a voltage comparatoremploying a circuit constitution pertaining to the reverse signalobtained from the window comparator as an example of the hysteresislevel setting means (hereinafter referred to as the “windowcomparator”), and the hysteresis level is determined by the output ofthe A phase sensor 35A and the output of the B phase sensor 35B beinginput and compared with the input value of the variable resistancecontrol circuit 136. Reference numeral 132 is a switch circuit forswitching whether to control A coil with the A1 phase drive waveform 84Aor the A2 phase drive waveform, and the same applies to the B phasecoil. Reference numeral 134 is the FV converter for converting thefrequency of the output value of the A phase sensor into a voltagevalue, and, by supplying this to the electronic VR control circuit 136,the value of resistance is determined, and the hysteresis level is set.In other words, as a result of making the hysteresis level variable, theduty of the rectangular wave is changed, and the torque control of themotor characteristics is enabled. For example, upon starting the motor,the hysteresis level is set to minimum, and the motor is driven givingpreference to the torque and sacrificing the efficiency. Further, whenthe motor is in a state of operational stability, the hysteresis levelis set to maximum to drive the motor giving preference to highefficiency. The hysteresis adjustment volume (v) may also be controlledwith the CPU. The control circuit 93 offers the selection of the mode ofexciting the A phase coil and B phase coil and rotating the rotor, andthe mode of exciting either phase and rotating the rotor.

FIG. 12 is control waveform diagram in a case of attempting to rotatethe rotor in a stopped state, and, when the hysteresis level is set tominimum, the window comparator 130 compares the sensor output value andhysteresis level, the output value of the sensor is converted into alogic quantity, an excitation signal of a high duty ratio is switchedand supplied to from the multiplexer 132 to the A phase coil array and Bphase coil array, and the motor attempts to rotate at a high torque. Asshown in FIG. 13, when the hysteresis level is set to maximum in a statewhere the rotor is rotating stably, an excitation signal of a low dutyratio is applied to the respective phase coil arrays, and the drivetorque of the motor will decrease. Nevertheless, the motor can beoperated at a high efficiency.

FIG. 14 is a diagram showing the circuit constitution in a case ofperforming PWM control, without depending on the control of thehysteresis level, based on the analog sensor output. The PWM converter160 is supplied with a comparative wave in which the reference frequencysignal from the PLL circuit 162 was divided, and, as a result of thiscomparative wave and the analog detection value from the A phase sensorand B phase sensor being compared, a duty-adjusted signal wave issupplied to the respective phase coil arrays. When the peak of theanalog output value is adjusted with the auto gain controls 102, 104, asa result of the frequency of the comparative signal of the PLL circuit162 being controlled, and suitably setting these with the likes of a CPUaccording to the requested torque of the motor, as shown in FIG. 15, thePWM output can be obtained from the sensor output. Incidentally, in theforegoing embodiments, although the permanent magnet array was explainedas a rotor, this may also be a linear motor that moves linearly.

FIG. 16 is a diagram showing the second example of the drive circuit,and the drive circuits of the A phase coil and B phase coil formedseparated in the circuit of FIG. 5 are formed as a single drive circuit.To explain with reference to FIG. 17, during the period of T1, TR1 andTR7 are turned on with the sensor output, and the excitation current inthe direction of IA1 supplied from the power source flows from thetransistor TR1 to the A phase coil 16, and to the earth via thetransistor TR7. During the period of T2, TR3 and TR7 are turned on, andthe excitation current from the power source passes through the B phasecoil in the direction of IB1, passes through TR7 and arrives at theearth. During the period of T3, TR2 is turned on, TR8 is turned on, andthe excitation current from the power source flows to the direction ofthe IA2 and arrives at the earth. During the period of T4, TR4 is turnedon, TR8 is turned on, and the excitation current from the power sourceto the direction of the IB2 and arrives at the earth.

FIG. 18 is shows the sensor direct drive system according to the presentinvention; in other words, it is a circuit diagram in a case of adoptingthe drive system of directly inputting the detection signal from thesensor to the drive circuit for driving the coil in a stepping motor.Reference numeral 190 is a rotor comprising a plurality of permanentmagnets, wherein reference numeral 192 is an A-A′ phase coil, referencenumeral 194 is a B-B′ phase coil, reference numeral 34A is an A phasesensor, and reference numeral 34B is a B phase sensor. FIG. 19 is a coildrive timing chart, and the A phase sensor output is supplied as thecoil excitation current to the A-A′ phase coil drive circuit, and the Bphase sensor output is supplied to the B-B′ phase coil drive circuit.The shaded portions in FIG. 19 allow the control of the normalrotation/reverse rotation of the rotor via switching the polarity.According to this embodiment, the drive yielding point caused by theload change of the stepping motor can be eliminated.

FIG. 20 is a block diagram of the digital regeneration/power generationcontrol based on an analog sensor comprising the wind comparator with ahysteresis adjustment electronic VR. When the output of the A phasesensor 34A exceeds the fluctuation margin of the hysteresis level, “H”of the A phase TP or A phase BT is output to the OR circuit 200, andthis is output as the A phase regenerative enabling signal to theincoming control circuit described later. The same applies to the outputof the B phase sensor 34B. Reference numeral 202 is the OR circuit.

FIG. 21 is a waveform diagram showing a case when the hysteresisadjustment electronic VR is small and the regenerative energy ismaximum, and FIG. 22 is a waveform diagram showing a case when thehysteresis adjustment electronic VR is maximum and the regenerativeenergy is minimum. In the case of a high load (strong regenerativebraking state), the duty ratio of the regenerative enabling signal ofthe respective phases will become high, and, when the regenerativeenabling signal is in the period of “H”, the regenerative current fromthe respective coils of the A phase and B phase is supplied to the load(battery). This is the state illustrated in FIG. 21. Meanwhile, in thecase of a low load (weak regenerative braking state), as shown in FIG.22, the duty ratio of the enabling signal of the respective phases willbecome small, and when the regenerative enabling signal is in the periodof “H”, the regenerative current from the respective phase coils issupplied to the load.

FIG. 23 is a diagram showing the functional block diagram of theincoming control from the respective phase coils, and, in accordancewith the switching of the H or L of the A phase regenerative enablingsignal, the transistors 230 and 232 will be alternately turned on viathe inverters 232A and 232B when the foregoing signal is supplied, andthe regenerative current which has been rectified with the rectifyingmeans 231 and smoothed with the smoothing circuit 240 will generatebetween the + power transmission terminal and − power transmissionterminal. The same applies to the B phase coil side. FIG. 24 shows theenergy converter of the regenerative current, wherein reference numeral240 is the DC/DC converter, reference numeral 242 is the DC/ACconverter, and reference numeral 244 is a chemical converter (battery).

Incidentally, the foregoing constitution, as shown in FIG. 25(1) andFIG. 25(2), may also be adopted in the structure where the A phase coil16 and B phase coil 18, and the rotor 20 formed from a permanent magnetface each other in the radial direction. FIG. 25(1) is a plan view ofthe motor, and FIG. 25(2) is the A-A′ cross section of FIG. 25(1).Although the stator was explained as the two phases of A phase and Bphase, the rotation/torque will decrease, but an independent drive andregeneration based on a single phase is also possible. As a result offluctuating the magnetic field intensity by making the distance betweenthe rotor and the A phase and B phase of the stator variable, therotation/torque characteristics can also be made variable. Therotation/torque characteristics can also be made variable by changingthe establishment position angle of the A phase/B phase of the stator.

According to the embodiments described above, since the output of thesensor of the respective phases for detecting the magnetic field changeaccompanying the rotation of the rotor is directly supplied to thetwo-phase electromagnetic coils set upon shifting the angles, the rotorcan be rotated with a weak current (micro order level) during the torquerequest operation upon starting the drive of the motor.

1. A drive circuit for an AC motor, the AC motor having a stator with acombination of a coil body, a movable body with a permanent magnet and asensor, the coil body having a plurality of coils, the permanent magnethaving a plurality of magnet pole elements, the plurality of magnet poleelements being arranged to become alternating opposite poles, and thesensor being disposed at the stator, detecting a periodic magnetic fieldchange caused by movement of the permanent magnet and outputting ananalog signal, the drive circuit comprising: a frequency to voltageconverter that converts a frequency of the analog signal to a voltagesignal; a hysteresis level setting part that sets a hysteresis levelbased on the voltage signal; a window comparator that compares theanalog signal and the hysteresis level, and creates the Pulse WideModulation signal; and a coil drive circuit that excites the pluralityof coils of the AC motor with the Pulse Wide Modulation signal.
 2. Adrive circuit according to claim 1, further comprising a controller anda switching circuit, the controller that creates a command signalcorresponding to a drive mode of the AC motor, and the switching circuitthat changes the polarity of the Pulse Wide Modulation signal to thecoil drive circuit, according to the command signal.
 3. A drive circuitaccording to claim 1, further comprising a controller and a switchingcircuit, the coil body has two phase coil arrays, the controller thatcreates a command signal corresponding to a drive mode of the AC motor,and the switching circuit that changes the supply of the Pulse WideModulation signal from one phase coil array to the other, according tothe command signal.
 4. A drive circuit according to claim 1, wherein thesensor is able to linearly detect a position of the moveable body in a2π area, the 2π area is an electric angle corresponding to two adjacentmagnet pole elements in a heteropolar arrangement of the plurality ofmagnet pole elements.
 5. A drive circuit according to claim 1, whereinthe sensor is a Hall element sensor.
 6. A drive circuit according toclaim 1, wherein the hysteresis level setting part is controlled by aCPU.